Laboratory heater



Nov. 9, 1943. J. A. SCHULDINER LABORATORY HEATER Filed Dec; 18, 1942 JA c 05 Ase/45R SCHULD/NER INVENTOR Fig- 5.

ATTORNEY Patented Nov. 9, 1943 UNITED STATES PATENT OFFICE I I a f a'ssasssy I I LABORATORY HEATER,

Jacob Ascher :Schuldiner, New York, 'N. Y. Application Decemberlil, 1 94 2 Serial No. 469,493

' 3 Claims. ci.;219 a 2 (Granted under the act of March 3, 1883, as

, amended Apirl 30, 1928; 370 0. G. 757) The invention'described herein, may be made and used by and for the Government of the United States for governmental purposes without the payment to me of any royalty therefor. a

The inventionarelates to laboratory heaters, and aims generally to improve the same.

Objects of the invention, severally and collectively, are to provide a heater of the class described which may be produced more cheaply than such heaters heretofore employed by the art; in which much higher heats can be used than is ordinarily the case, thereby speeding up the work;

in'which the heating elements employed are of a common type easily and cheaply replaced at low cost; and in which operating temperatures can be attained in a matter of minutes, compared with hours for ordinary mufilers.

Further objects and advantages of the invention will be apparent from the following detailed description of the preferred embodiment illustrated in the drawing, in which- Figs. 1 and 2 are front and side elevations of the complete heater device with a portion of the vertical height of the racks cut away and Figs. 3, 4 and 5 aresections taken as indicated by the arrows on lines 3-3, 4-4 and 5-5 of Figs. 1', 3 and 4, respectively. I

Referring to the specific embodiment shown in the drawing, it will be seen that the laboratory heater of this invention is made up of four distinct parts, viz: the movable heat insulating deflector, A;iba're resistance wire heating elements, B; a base with an evaporating rack, C; and special means for adjusting the height of the reflector above the base, D. V

In the preferred form shown in the drawing, the reflector A is constructed as an inverted, sectioned, trough-like member formed of compressed asbestos-composition sheet such as that sold under the trade name Ti'ansite, and is provided with fin-like means, herein comprising two metal rack fins l0, adapted to engage in any of the several slots between the teeth of the height adjusting comb, and with two heat insulated laterally positioned, forwardly extending plow-type handles I I, herein formed with transite grips, suitably secured to the trough member as by the bolts or rivets shown. The heat reflecting trough, or hood, may be lined if desired, with non-corrosive metal, for example stainless steel or Monel metal, or with other refractory materials such as porcelain, fine clay, alumdum, sillimanite, quartz or the like, or if desired, may be made entirely of such materials. In the form shown, the hood is assembled from top, side, back and inclined front members all easily cut from flat sheet material, which members are secured together by screws or other suitable fastenings, as shown. If desired, the trough may be subdivided by partitions to form a ganged multiple unit heater, which decreases the cost of the individual heater units and increases the efiiciency of the apparatus. Two such partitions (l2, Fig. 3) are employed in the form shown, suitably secured to divide the trough with a three circuit embodiment.

The bare resistance wire heating elements B, lodged inthe respective hood compartments, may beof any desired form, butpreferably are in the form of self-containedcommercial units capable of easy replacement as shown in Figs. 3, 4 and 5. In the form shown, these units consist of a porcelain or similar ceramic tube 20 (Fig, 4) having a spiral groove inwhich the coil 2| of resistance wire is received, and having terminal and sup-- porting bands 22 electrically connected to the ends of coil 2| and provided'with supporting legs 23having inturned feet 24, which are secured to the top wall of thehood A by through-bolts 25, to which electrical connection is made in any suitable manner, bus-bars 26 being preferred in the ganged multiple unit embodiment shown, which in turn are connected to heater cord 21, a sheet of asbestos insulation 28 being employed if the cord passes under one bus-bar to connect with the other. In the form shown, the bus-bar 26 and connections thereto are housed in an insulating casing 29 the removable cover of which facilitates change of resistance units B. Y

The base C (Figs. 1 and 2) in the preferred form comprises a flatiron casting 30 covered entirely by an insulating sheet of "Transite or the like 3|, suitable secured, as by bolting to the casting, and carrying means for supporting specimen-containingdishes, herein comprising two notched metal supports 32 of angle form bolted to the base, on which are carried two removable heavy wires 33 making up the evaporation rack.

The special means D -(Figs. 1 and 2) for adjusting the height of the reflector, cooperates in a simple and eflective manner with the rack fins l0 and plow-type handles II. It comprises combbar means extending vertically from the base 30,

herein in the form of a pair of combor rackmembers 40, having angled feet 4| secured to the base 30 and which may be provided with complementary angle-braces 42 to complete T feet for more rigid securement to the base. The two comb-members 40 are joined together at their tops by a cross brace 43, secured as by projection of reduced end sections of the brace through ability to attach suificiently high temperatures,

and particularly in the inability to quickly and easily change the temperatures applied. Withthe present arrangement the versatile in these regards. from about 100 steps. I

It evaporates liquids at high temperatures device is extremely It gives temperatures C. to over 500 (2., in very small without boiling or spattering. its heat'ing' up period is short; in two to five minutestemperatures up to 500 (1., can be obtained with ease, with three 400 watt units, which all together use only about the samecurrent, A. C. -or D. (3;, as is usedby an ordinary hot, plate. In the usual ashing procedure there are actually three steps involved; jfirst, the removal of moisture; second, the removal of volatile organic matter and carbonization; and third, the actual ashing. With substances ordinarily diflicult to handle, as sardines, accurate control of temperatures necessary to avoid losses may be accomplished with the present heater. Thus-a 100 gram sample of sardine in a porcelain dish may be first be dried at a temperature of about 150 C., or less. The ixamperature may then be easily and quickly increased somewhat to burn or fume off the fats and oils, and leave the re maining organic matter completely charred. The temperature may then be further'increased for ashingpf this residue, if .deisred, which ashing will preferably be conducted at a low ashing temperature. All this may bedone in a minimum of time without once removing the specimen, because the very easilyrmovable heater and rack combination makes possible instantaneoustemperature changes from the lowest to the highest or to any intermediate values, of temperature.

In this'connection ,pyrometric readings have shown that in an embodiment having a trough about 5" x 11" x 2 /2 deep, employing-three 400 watt units of the type shown; and having rack-bars D about 9 inches tall provided with 16 slots from 2 /2 to 8 A inches above thesurtace 3|, each of the 16 positions of the heating units represents a quite constant and reproducible temperature. T.hus, by calibrating the rack posi--' tions, the temperature desired can be immediately attained.

The combination of the plow-type handles II, with the manner of supporting the heater in rack D, is particularly advantageous. The handles are removed from the heated zone andare positioned in such manner as to make almost iii instinctive the slight pulling forward of the heater A from rack D; the maintenance of a horizontal position of the heater A during transfer, either manually or by permitting the fins H to drop from slot to slot of the rack D, pair by pair, with slight fore and aft tilting of the handles; and the thrusting of the fins I l into firm engagement in the slots 44 at the selected temperature level. Moreover, with the present arrangement the speed of ashing of materials which burn or ash more or less difiicultly is greatly-accelerated by the greater air supply, relative to the mufller procedure, and the ashing and burning proceeds at a much lower temperature than that in the usual mufiie, a matter very important in the determination of lead, sodium and other substances which volatilize if heated excessively.

Evaporation may be made at much higher temperatures than the usual C., or less of the water-bath as the heating is almost entirely froim above, and boiling from the bottom and splattering due to superheating cannot take place. For example, 100 cc. of water or water solution has been evaporated in platinum dishes in 25 to 30 minutes with this device, without any spattering; and the device in the form shown may thus handle three or foursuch samples, or different samples, at the same time.

Havingdescribed a preferred embodiment illustrativeof my invention, what I claim is:

1. A laboratory heater for rapid evaporation, drying and charring of laboratory specimens, cc-mprisinga base provided with means for supporting specimen-containing dishes, comb-bar means extending vertically from said base, an inverted trough-like reflector having insulated, laterally positioned, forwardly extending plowtype handlesand adapted to overly said specimen-dish supporting means, and bare resistance wire radiant-heating means within said troughlike reflector, said reflector having fin-like means adapted to enter any or the several slots between the teeth of said comb-bar means to position said 1 heating means at various selected predetermined distancesv above said specimen-dish supporting means, whereby the specimens may be subjected,

to different predetermined temperatures and the temperatures applied thereto may be quickly and. easily changed at will.

. '2. A heater-according to claim 1, in which trough-like reflector means is subdivided by p'ar-.

titions into a plurality of compartments each opening downwardly, and in which said radiant heating means consists of a number of individual radiant heating elements separately removable for replacement.

3. A heater according to claim 1, in which said specimen-dish supporting means consists of parallel heavy wires removably supported in notches presented by angle-member flanges supported by and projecting somewhat above the level of the base.

JACOB ASCHER SCHULDINER. 

